Process for the preparation of polyolefins

ABSTRACT

A process for the preparation of an olefin polymer by polymerization or copolymerization of an olefin of the formula R a —CH═CH—R b , in which R a  and R b  are identical or different and are a hydrogen atom or a hydrocarbon radical having 1 to 14 carbon atoms, or R a  and R b , together with the atoms connecting them, can form a ring, at a temperature of from −60 to 200° C., at a pressure of from 0.5 to 100 bar, in solution, in suspension or in the gas phase, in the presence of a catalyst formed from a metallocene in the meso-form or a meso:rac mixture, with meso:rac&gt;1:99, as transition-metal compound and a cocatalyst, wherein the metallocene is a compound of the formula I,                    
     in which M 1  is Zr or Hf, R 1  and R 2  are identical or different and are methyl or chlorine, R 3  and R 4  are identical or different and are methyl, isopropyl, phenyl, ethyl or trifluoromethyl, R 4  and R 5  are hydrogen or as defined for R 3  and R 6 , or R 4  forms an aliphatic or aromatic ring with R 6 , or adjacent radicals R 4  form a ring of this type, and R 7  is a                    
     radical, and m plus n is zero or 1.

This is a divisional application under 37 C.F.R. §1.53, of priorapplication Ser. No. 08/914,387 (U.S. Pat. No. 6,028,152), filed on Aug.18, 1997, which is a divisional application of prior application Ser.No. 08/484,457 (U.S. Pat. No. 5,693,836), filed on Jun. 7, 1995, whichis a divisional application of Ser. No. 08/107,187 filed on Aug. 16,1993 (U.S. Pat. No. 5,672,668).

For the preparation of highly isotactic polyolefins by means ofstereospecific racemic metallocene/cocatalyst systems, the highestpossible isotacticity is desired. This means that very stereoselectiveracemic metallocene types are employed which are able to build uppolymer chains having very few construction faults. The consequence ofthis is that products having high crystallinity, high melting point andthus also high hardness and excellent modules of elasticity in flexingare obtained as desired.

However, it is disadvantageous that these polymers are difficult toprocess, and in particular problems occur during extrusion, injectionmolding and thermoforming. Admixing of flow improvers and othermodifying components could help here, but results in the good productproperties, such as, for example, the high hardness, being drasticallyreduced. In addition, tackiness and fogging also occur. The object wasthus to improve the processing properties of highly isotacticpolyolefins of this type without in this way impairing the goodproperties of the moldings produced therefrom.

Surprisingly, we have found that it rac/meso mixtures of certainmetallocenes are used, the processing problems can be eliminated withoutthe abovementioned good product properties being lost.

In addition, the use of these specific metallocenes in their puremeso-form makes it possible to prepare high-molecular-weight atacticpolyolefins which can be homogeneously admixed, as additives, with otherpolyolefins.

This was not possible with the low-molecular weight polyolefinsaccessible hitherto due to the large differences in viscosity betweenthe polyolefin matrix and the atactic component.

Such admixtures improve polyolefin moldings with respect to theirsurface gloss, their impact strength and their transparency. Inaddition, the processing properties of such polyolefins are likewiseimproved by admixing the high-molecular-weight atactic polyolefin.Likewise, tackiness and fogging do not occur.

Homogeneous miscibility of the atactic component is so important becauseonly with a homogeneous material can a usable molding with a goodsurface and long service life be produced and only in the case ofhomogeneous distribution do the qualities of the atactic component comeout in full.

The invention thus relates to the preparation of polyolefins which

1) are atactic, i.e. have an isotactic index of ≦60%, and arehigh-molecular, i.e. have a viscosity index of >80 cm³/g and a molecularweight M_(w) of >100,000 g/mol with a polydispersity M_(w)/M_(n) of≦4.0, or

2) comprise at least two types of polyolefin chains, namely

a) a maximum of 99% by weight, preferably a maximum of 98% by weight, ofthe polymer chains in the polyolefin as a whole comprise α-olefin unitslinked in a highly isotactic manner, with an isotactic index of >90% anda polydispersity of ≦4.0, and

b) at least 1% by weight, preferably at least 2% by weight, of thepolymer chains in the polyolefin as a whole comprise atactic polyolefinsof the type described under 1).

Polyolefins which conform to the description under 2) can either beprepared directly in the polymerization or are prepared by melt-mixingin an extruder or compounder.

The invention thus relates to a process for the preparation of an olefinpolymer by polymerization or copolymerization of an olefin of theformula R^(a)—CH═CH—R^(b), in which R^(a) and R^(b) are identical ordifferent and are a hydrogen atom or a hydrocarbon radical having 1 to14 carbon atoms, or R^(a) and R^(b), together with the atoms connectingthem, can form a ring, at a temperature of from −60 to 200° C., at apressure of from 0.5 to 100 bar, in solution, in suspension or in thegas phase, in the presence of a catalyst formed from a metallocene astransition-metal compound and a cocatalyst, wherein the metallocene is acompound of the formula I which is used in the pure meso-form for thepreparation of polyolefins of type 1 and used in a meso:rac ratio ofgreater than 1:99, preferably greater than 2:98, for the preparation oftype 2 polyolefins,

in which

M¹ is a metal from group IVb, Vb or VIb of the Periodic Table,

R¹ and R² are identical or different and are a hydrogen atom, aC₁-C₁₀-alkyl group, a C₁-C₁₀-alkoxy group, a C₆-C₁₀-aryl group, aC₆-C₁₀-aryloxy group, a C₂-C₁₀-alkenyl group, a C₇-C₄₀-arylalkyl group,a C₇-C₄₀-alkylaryl group, at C₈-C₄₀-arylalkenyl group, or a halogenatom,

the radicals R⁴ and R⁵ are identical or different and are a hydrogenatom, a halogen atom, a C₁-C₁₀-alkyl group, which may be halogenated, aC₆-C₁₀-aryl group, which may be halogenated, and an —NR¹⁰ ₂, —SR¹⁰,—OSiR¹⁰ ₃, —SiR¹⁰ ₃ or —PR¹⁰ ₂ radical in which R¹⁰ is a halogen atom, aC₁-C₁₀-alkyl group or a C₆-C₁₀aryl group,

R³ and R⁶ are identical or different and are as defined as for R⁴, withthe proviso that R³ and R⁶ are not hydrogen,

or two or more of the radicals R³ to R⁶, together with the atomsconnecting them, form a ring system,

═BR¹¹, ═AlR¹¹, —Ge—, —Sn—, —O—, —S—, ═SO, ═SO₂, ═NR¹¹, ═CO, ═PR¹¹ or═P(O)R¹¹, where

R¹¹, R¹² and R¹³ are identical or different and are a hydrogen atom, ahalogen atom, a C₁-C₁₀-alkyl group, a C₁-C₁₀-fluoroalkyl group, aC₆-C₁₀-aryl group, a C₆-C₁₀-fluoroaryl group, a C₁-C₁₀-alkoxy group, aC₂-C₁₀-alkenyl group, a C₇-C₄₀-arylalkyl group, a C₈-C₄₀-arylalkenylgroup or a C₇-C₄₀-alkylaryl group, or R¹¹ and R¹² or R¹¹ and R¹³, ineach case together with the atoms connecting them, form a ring,

M² is silicon, germanium or tin,

R⁸ and R⁹ are identical or different and are as defined for R¹¹, and

m and n are identical or different and are zero, 1 or 2, where m plus nis zero, 1 or 2.

Alkyl is straight-chain or branched alkyl. Halogen (halogenated) meansfluorine, chlorine, bromine or iodine, preferably fluorine or chlorine.

The substitutents R³, R⁴, R⁵ and R⁶ may be different in spite of thesame indexing.

The catalyst to be used for the process according to the inventioncomprises a cocatalyst and a metallocene of the formula I.

In the formula I, M¹ is a metal from group IVb, Vb or VIb of thePeriodic Table, for example titanium, zirconium, hafnium, vanadium,niobium, tantalum, chromium, molybdenum or tungsten, preferablyzirconium, hafnium or titanium.

R¹ and R² are identical or different and are a hydrogen atom, a C₁-C₁₀-,preferably C₁-C₃-alkyl group, a C₁-C₁₀-, preferably C₁-C₃-alkoxy group,a C₄-C₁₀-, preferably C₆-C₈-aryl group, a C₆-C₁₀-, preferablyC₄-C₈-aryloxy group, a C₂-C₁₀-, preferably C₂-C₆-alkenyl group, aC₇-C₄₀-, preferably C₇-C₁₀-arylalkyl group, a C₇-C₄₀-, preferably aC₇-C₁₂-alkylaryl group, a C₈-C₄₀-, preferably a C₈-C₁₂-aryalkenyl group,or a halogen atom, preferably chlorine.

The radicals R⁴ and R⁵ are identical or different and are a hydrogenatom, a halogen atom, preferably a fluorine, chlorine or bromine atom, aC₁-C₁₀-, preferably C₁-C₄-alkyl group, which may be halogenated, aC₆-C₁₀-, preferably a C₆-C₉-aryl group, which may be halogenated, an—NR¹⁰ ₂, —SR¹⁰, —OSiR¹⁰ ₃, —SiR¹⁰ ₃ or ═PR¹⁰ ₂ radical, in which R¹⁰ isa halogen atom, preferably a chlorine atom, or a C₁-C₁₀-, preferably aC₁-C₃-alkyl group, or a C₆-C₁₀- preferably C₆-C₈-aryl group. R⁴ and R⁵are particularly preferably hydrogen, C₁-C₄-alkyl or C₆-C₉-aryl.

R³ and R⁶ are identical or different and are defined for R⁴, with theproviso that R³ and R⁶ must not be hydrogen. R³ and R⁶ are preferably(C₁-C₄)-alkyl or C₆-C₉-aryl, both of which may be halogenated, such asmethyl, ethyl, propyl, isopropyl, butyl, isobutyl, trifluoromethyl,phenyl, tolyl or mesityl, in particular methyl, isopropyl or phenyl.

Two or more of the radicals R³ to R⁶ may alternatively, together withthe atoms connecting them, form an aromatic or aliphatic ring system.Adjacent radicals, in particular R⁴ and R⁶, together preferably form aring.

═BR¹¹, ═AlR¹¹, —Ge—, —Sn—, —O—, —S—, ═SO, ═SO₂, ═NR¹¹, ═CO, ═PR¹¹ or═P(O)R¹¹, where R¹¹, R¹² and R¹³ are identical or different and are ahydrogen atom, a halogen atom, a C₁-C₁₀-, preferably C₁-C₄-alkyl group,in particular a methyl group, a C₂-C₁₀-fluoroalkyl group, preferably aCF₃ group, a C₆-C₁₀-, preferably C₆-C₈-aryl group, a C₆-C₁₀-fluoroarylgroup, preferably a pentafluorophenyl group, a C₁-C₁₀-, preferably aC₁-C₄-alkoxy group, in particular a methoxy group, a C₂-C₁₀-, preferablyC₂-C₄-alkenyl group, a C₇-C₄₀-, preferably C₇-C₁₀-arylalkyl group, aC₈-C₄₀-, preferably C₈-C₁₂-arylalkenyl group or a C₇-C₄₀-, preferablyC₇-C₁₂-alkylaryl group, or R¹¹ and R¹² or R¹¹ and R¹³, in each casetogether with the atoms connecting them, form a ring.

M² is silicon, germanium or tin, preferably silicon or germanium.

R⁷ is preferably ═CR¹¹R¹², ═SiR¹¹R¹², ═GeR¹¹R¹², —O—, —S—, ═SO, ═PR¹¹ or═P(O)R¹¹.

R⁸ and R⁹ are identical or different and are as defined for R¹¹.

m and n are identical or different and are zero, 1 or 2, preferably zeroor 1, where m plus n is zero, 1 or 2, preferably zero or 1.

Particularly preferred metallocenes are thus the compounds of theformulae A and B

where

M¹ is Zr or Ef; R¹ and R² are methyl or chlorine; R³ and R⁶ are methyl,isopropyl, phenyl, ethyl or trifluoromethyl;

R⁴ and R⁵ are hydrogen or as defined for R³ and R⁶, or R⁴ can form analiphatic or aromatic ring with R⁶; the same also applies to adjacentradicals R⁴; and R⁸, R⁹, R¹¹ and

R¹² are as defined above, in particular the compounds I listed in theworking examples.

This means that the indenyl radicals of the compounds I are substituted,in particular, in the 2,4-position, in the 2,4,6-position, in the2,4,5-position or in the 2,4,5,6-position, and the radicals in the 3-and 7-positions are preferably hydrogen.

Nomenclature

The metallocenes described above can be prepared by the followingreaction scheme, which is known from the literature:

The compounds are formed from the synthesis as rac/meso mixtures. Themeso or rac form can be increased in concentration by fractionalcrystallization, for example in a hydrocarbon. This procedure is knownand is part of the prior art.

The cocatalyst used according to the invention is preferably analuminoxane of the formula (II)

for the linear type and/or of the formula (III)

for the cyclic type, where, in the formulae (II) and (III), the radicalsR¹⁴ may be identical or different and are a C₁-C₆-alkyl group, aC₆-C₁₈-aryl group, benzyl or hydrogen, and p is an integer from 2 to 50,preferably from 10 to 35.

The radicals R¹⁴ are preferably identical and are preferably methyl,isobutyl, phenyl or benzyl, particularly preferably methyl.

If the radicals R¹⁴ are different, they are preferably methyl andhydrogen or alternatively methyl and isobutyl, where hydrogen andisobutyl are preferably present to the extent of 0.01-40% (number ofradicals R¹⁴).

The aluminoxane can be prepared in various ways by known processes. Oneof the methods is, for example, to react an aluminum hydrocarboncompound and/or a hydridoaluminum hydrocarbon compound with water (ingas, solid, liquid or bonded form—for example as water ofcrystallization) in an inert solvent (such as, for example, toluene). Inorder to prepare an aluminoxane containing different alkyl groups R¹⁴two different trialkylaluminum compounds (AlR₃+AlR′₃) corresponding tothe desired composition are reacted with water (cf. S. Pasynkiewicz,Polyhedron 9 (1990) 429 and EP-A 302 424).

The precise structure of the aluminoxanes II and III is unknown.

Regardless of the preparation method, all the aluminoxane solutions havein common a varying content of unreacted aluminum starting compound, infree form or as an adduct.

It is possible to preactivate the metallocene by means of an aluminoxaneof the formula (II) and/or (III) before use in the polymerizationreaction. This significantly increases the polymerization activity andimproves the grain morphology.

The preactivation of the transition-metal compound is carried out insolution. The metallocene is preferably dissolved in a solution of thealuminoxane in an inert hydrocarbon. Suitable inert hydrocarbons arealiphatic and aromatic hydrocarbons. Toluene is preferably used.

The concentration of the aluminoxane in the solution is in the rangefrom about 1% by weight to the saturation limit, preferably from 5 to30% by weight, in each case based on the solution as a whole. Themetallocene can be employed in the same concentration, but is preferablyemployed in an amount of from 10⁻⁴ to 1 mol per mol of aluminoxane. Thepreactivation time is from 5 minutes to 60 hours, preferably from 5 to60 minutes. The reaction is carried out at a temperature of from −78° C.to 100° C., preferably from 0 to 70° C.

The metallocene can also be prepolymerized or applied to a support.Prepolymerization is preferably carried out using the (or one of the)olefin(s) employed in the polymerization.

Examples of suitable supports are silica gels, aluminum oxides, solidaluminoxane or other inorganic support materials. Another suitablesupport material is a polyolefin powder in finely divided form.

According to the invention, compounds of the formulae R_(x)NH_(4−x)BR′₄,R_(x)PH_(4−x)BR′₄, R₃CBR′₄ or BR′₃ can be used as suitable cocatalystsinstead of or in addition to an aluminoxane. In these formulae, x is anumber from 1 to 4, preferably 3, the radicals R are identical ordifferent, preferably identical, and are C₁-C₁₀-alkyl, or C₆-C₁₈-aryl or2 radicals R, together with the atom connecting them, form a ring, andthe radicals R′ are identical or different, preferably identical, andare C₆-C₁₈-aryl, which may be substituted by alkyl, haloalkyl orfluorine.

In particular, R is ethyl, propyl, butyl or phenyl, and R′ is phenyl,pentafluorophenyl, 3,5-bistrifluoromethyl-phenyl, mesityl, xylyl ortolyl (cf. EP-A 277 003, EP-A 277 004 and EP-A 426 638).

When the abovementioned cocatalysts are used, the actual (active)polymerization catalyst comprises the product of the reaction of themetallocene and one of said compounds. For this reason, this reactionproduct is preferably prepared first outside the polymerization reactorin a separate step using a suitable solvent.

In principle, suitable cocatalysts are according to the invention anycompounds which, due to their Lewis acidity, are able to convert theneutral metallocene into a cation and stabilize the latter (“labilecoordination”). In addition, the cocatalyst or the anion formedtherefrom should not undergo any further reactions with the metallocenecation formed (cf. EP-A 427 697).

In order to remove catalyst poisons present in the olefin, purificationby means of an alkylaluminum compound, for example Alme₃ or AlEt₃, isadvantageous. This purification can be carried out either in thepolymerization system itself, or the olefin is brought into contact withthe Al compound before addition to the polymerization system and issubsequently separated off again.

The polymerization or copolymerization is carried out in known manner insolution, in suspension or in the gas phase, continuously or batchwise,in one or more steps, at a temperature of from −60 to 200° C.,preferably from 30 to 80° C., particularly preferably at from 50 to 80°C. The polymerization or copolymerization is carried out using olefinsof the formula R^(a)—CH═CH—R^(b). In this formula, R^(a) and R^(b) areidentical or different and are a hydrogen atom or an alkyl radicalhaving 1 to 14 carbon atoms. However, R^(a) and R^(b), together with thecarbon atoms connecting them, may alternatively form a ring. Examples ofsuch olefins are ethylene, propylene, 1-butene, 1-hexene,4-methyl-1-pentene, 1-octene, norbornene and norbonadiene. Inparticular, propylene and ethylene are polymerized.

If necessary, hydrogen is added as molecular weight regulator and/or toincrease the activity. The overall pressure in the polymerization systemis 0.5 to 100 bar. The polymerization is preferably carried out in theindustrially particularly relevant pressure range of from 5 to 64 bar.

The metallocene is used in a concentration, based on the transitionmetal, of from 10⁻³ to 10⁻⁸ mol, preferably from 10⁻⁴ to 10⁻⁷ mol, oftransition metal per dm³ of solvent or per dm³ of reactor volume. Thealuminoxane is used in a concentration of from 10⁻⁵ to 10⁻¹ mol,preferably from 10⁻⁴ to 10⁻² mol, per dm³ of solvent or per dm³ ofreactor volume. The other cocatalysts mentioned are used inapproximately equimolar amounts with respect to the metallocene. Inprinciple, however, higher concentrations are also possible.

If the polymerization is carried out as a suspension or solutionpolymerization, an inert solvent which is customary for the Zieglerlow-pressure process is used. For example, the process is carried out inan aliphatic or cycloaliphatic hydrocarbon; examples of suchhydrocarbons which may be mentioned are propane, butane, pentane,hexane, heptane, isooctane, cyclohexane and methylcyclohexane.

It is also possible to use a benzine or hydrogenated diesel oilfraction. Toluene can also be used. The polymerization is preferablycarried out in the liquid monomer.

If inert solvents are used, the monomers are metered in as gases orliquids.

The polymerization can have any desired duration, since the catalystsystem to be used according to the invention only exhibits a slight dropin polymerization activity as a function of time.

The process according to the invention is distinguished by the fact thatthe meso-metallocenes described give atactic polymers of high molecularweight in the industrially particularly relevant temperature rangebetween 50 and 80° C. rac/meso mixtures of the metallocenes according tothe invention give homogeneous polymers with particular good processingproperties. Moldings produced therefrom are distinguished by goodsurfaces and high transparency. In addition, high surface hardnesses andgood moduli of elasticity in flexing are characteristics of thesemoldings.

The high-molecular-weight atactic component is not tacky, and themoldings are furthemore distinguished by very good fogging behavior.

The examples below serve to illustrate the invention in greater detail.

The following abbreviations are used:

VI = viscosity index in cm³/g M_(w) = weight average molecular weightdetermined in g/mol by gel permeation chromato- M_(w)/M_(n) =polydispersity graphy m.p. = melting point determined by DSC (20° C./minheating/cooling rate) II = isotactic index (II = mm + ½ mr) determinedby ¹³C-NMR spectroscopy n_(iso) = isotactic block length (n_(iso) = 1 +2 mm/mr) n_(syn) = syndiotactic block length (n_(syn) = 1 + 2 rr/mr)MFI/(230/5) = melt flow index, measured in accordance with DIN 53735; indg/min.

EXAMPLES 1 TO 16

A dry 24 dm³ reactor was flushed with propylene and filled with 12 dm³of liquid propylene. 35 cm³ of a toluene solution of methylaluminoxane(corresponding to 52 mmol of Al, mean degree of oligomerization p=18)were then added, and the batch was stirred at 30° C. for 15 minutes. Inparallel, 7.5 mg of the meso-metallocene shown in Table 1 were dissolvedin 13.5 cm³ of a toluene solution of methylaluminoxane (30 mol of Al)and preactivated by standing for 15 minutes. The solution was thenintroduced into the reactor and heated to 70° C. or 50° C. (Table 1, 10°C./min). The polymerization duration was 1 hour. The polymerization wasterminated by addition of 20 dm³ (s.t.p.) of CO₂ gas. The metalloceneactivities and the viscosity indices of the atactic polymers obtainedare collated in Table 1. The ¹³C-NMR analyses gave in all casesisotactic block lengths n_(iso) of <4, typically n_(iso)=2, and thesyndiotactic block length was typically likewise in the region of 2. Thetriad distributions mm:mr:rr were typically about 25:50:25, and theisotactic index (mm+½ mr) was less than 60%. The products were thereforeundoubtedly typical atactic polypropylenes. This is also confirmed bythe solubility in boiling heptane or in diethyl ether.

The DSC spectrum showed no defined melting point. T_(g) transitions wereobserved in the range from 0° C. to −20° C.

TABLE 1 Polymerization Activity temperature [kg of PP/g of VIMeso-metallocene [° C.] metallocene × h] [cm³/g] Ex.Me₂Si(2,4-dimethyl-1-indenyl)₂ZrCl₂ 50 35.7 125 1Me₂Si(2-methyl-4-isopropyl-1-indenyl)₂ZrCl₂ 70 60.4 93 2Me₂Si(2-ethyl-4-methyl-1-indenyl)₂ZrCl₂ 70 70.3 101 3Ph(Me)Si(2-methyl-4-isopropyl-1-indenyl)₂ZrCl₂ 50 20.6 120 4Me₂Si(2-methyl-4,5-benzoindenyl)₂ZrCl₂ 70 200.0 120 5Me₂Si(2-methyl-4,5-benzoindenyl)₂ZrCl₂ 50 60.4 150 6Me₂Si(2,4,6-trimethyl-1-indenyl)₂ZrCl₂ 50 30.1 163 7Me₂Si(2-methyl-4,6-diisopropyl-1- 50 24.5 89 8 indenyl)₂ZrCl₂Me₂Si(2-methyl-α-acenaphthindenyl)₂ZrCl₂ 50 49.3 224 9Me₂Si(2-methyl-α-acenaphthindenyl)₂ZrCl₂ 70 189.4 140 10Me₂Si(2-methyl-4-phenylindenyl)₂ZrCl₂ 70 64.5 131 11Me₂Si(2-methyl-4-phenyl-1-indenyl)₂ZrCl₂ 50 32.5 169 12Ethylene(2,4,6-trimethyl-1-indenyl)₂ZrCl₂ 70 145.5 124 13Ethylene(2-methyl-4,5-benzoindenyl)₂ZrCl₂ 50 94.9 109 14Methylethylene(2-methyl-g- 50 64.3 204 15 acenaphthindenyl)₂ZrCl₂Ph(Me)Si(2-methyl-g-acenaphthindenyl)₂ZrCl₂ 50 69.8 198 16

EXAMPLES 17 TO 23

Examples 1, 4, 7, 9, 12, 15 and 16 were repeated but the puremeso-metallocene was replaced by a rac:meso=1:1 mixture.

The polymers obtained were extracted with boiling ether or dissolved ina hydrocarbon having a boiling range of 140-170° C. and subjected tofractional crystallization; the high-molecular-weight atactic componentwas separated off and could thus be analyzed separately from theisotactic residue. The results are collated in Table 2. Products arenon-tacky, and moldings produced therefrom do not exhibit fogging andhave an excellent surface and transparency.

TABLE 2 Activity Ether-soluble Ether-insoluble Rac: meso = 1:1 [kg ofPP/g of atactic component isotactic component Ex. metallocene mixturemetallocene × h] % by weight VI [cm³/g] % by weight VI [cm³/g] 17Me₂Si(2,4-dimethyl-1- 69.5 25.4 117 74.6 216 indenyl)₂ZrCl₂ 18Ph(Me)Si(2-methyl-4- 102.3 12.0 124 88.0 280 isopropyl-1-indenyl)₂ZrCl₂19 Me₂Si(2,4,6-trimethyl-1- 114.0 18.5 152 71.5 245 indenyl)₂ZrCl₂ 20Me₂Si(2-methyl-g-acenaphth- 61.4 44.9 209 53.1 438 indenyl)₂ZrCl₂ 21Me₂Si(Si(2-methyl-4-phenyl- 334.5 5.5 177 94.5 887 1-indenyl)₂ZrCl₂ (5mg) 22 Methylethylene(2-methyl-g- 85.2 36.9 199 63.1 365acenaphthindenyl)₂ZrCl₂ 23 Pb(Me)Si(2-methyl-g-ace- 79.1 31.2 205 68.8465 naphthindenyl)₂ZrCl₂

EXAMPLES 24 TO 28

Example 5 was repeated, but the pure meso-form of the metallocene wasreplaced by rac:meso ratios of 98:2, 95:5, 90:10, 85:15 and 75:25. Theresults are collated in Table 3. A non-tacky powder is obtained, andmoldings produced therefrom have a good surface, are non-tacky and donot exhibit fogging. The molding hardness is good, as is thetransparency.

TABLE 3 Activity Ether-soluble Ether-insoluble [kg PP/g metallocenestactic component isotactic component Ex. Rac:meso × h] % by wt. VI[cm³/g] % by wt. VI [cm³/g] 24 98.2  436 0.95 134 99.05 285 25 95.5  4102.7 119 97.3 276 25 90.10 415 4.3 122 95.7 296 27 85.15 370 7.3 125 92.7300 28 75.25 347 15.2 130 84.8 280

EXAMPLE 29

Example 24 was repeated using 12 dm³ (s.t.p.) of hydrogen in thepolymerization system. The polymerization duration was 30 minutes. Themetallocene activity was 586 kg of PP/g of metallocene×h. Theether-soluble proportion was 1.1% by weight, with a VI of 107 cm³/g, andthe ether-insoluble proportion was 98.9% by weight, with a VI of 151cm³/g.

EXAMPLE 30

Example 25 was repeated, but 70 g of ethylene were metered incontinuously during the polymerization. The polymerization duration was45 minutes. The metallocene activity was 468 kg of PP/g ofmetallocene×h, the ethylene content of the copolymer was 3.3% by weight,and, according to ¹³C-NMR spectroscopy, the ethylene was incorporatedsubstantially in an isolated manner (random compolymer).

EXAMPLE 31

A dry 150 dm³ reactor was flushed with nitrogen and filled at 20° C.with 80 dm³ of a benzine cut having the boiling range from 100 to 120°C. from which the aromatic components had been removed. The gas spacewas then flushed with propylene until free of nitrogen, and 50 l ofliquid propylene and 64 cm³ of a toluene solution of methylaluminoxane(100 mmol of Al, p=18) were added. The reactor contents were heated to60° C., and the hydrogen content in the reactor gas space was adjustedto 0.1% by metering in hydrogen and was kept constant during the entirepolymerization time by further metering (checking on-line by gaschromatography), 10.7 mg of rac:meso (95:5) of the metallocenedimethylsilane-diylbis(2-methyl-4,5-benzoindenyl)zirconium dichloridewere dissolved in 32 cm³ of a toluene solution of methyl-aluminoxane (50mmol) and introduced into the reactor. The polymerization was carriedout in first step for 8 hours at 60° C. In a second step, 2.8 kg ofethylene were added rapidly at 47° C. and, after polymerization for afurther 5 hours at this temperature, the polymerization was completed bydischarging the reactor contents into a 280 l reactor containing 100 lof acetone. The polymer powder was separated off and dried for 48 hoursat 80° C./200 mbar. 21.4 kg of block copolymer powder were obtained.VI=359 cm³/g; M_(w)=402,000 g/mol, M_(w)/M_(n)=4.0; MFI (230/5)=9.3dg/min. The block copolymer contained 12.2% by weight of ethylene.Fractionation gave a content of 31.5% by weight of ethylene/propylenerubber and 3.7% by weight of atactic polypropylene, with a VI of 117cm³/g in the polymer as a whole.

EXAMPLE 32

The procedure was as in Examples 1-16, but the metallocene was thecompound meso-Me₂Si (2-methyl-4-(1-naphthyl)-1-indenyl)₂ZrCl₂. Theresults are collated in Table 4.

TABLE 4 Activity Polymerization [kg of PP/g of VI M_(w) temperature [°C.] metallocene x h] [cm³/g] M_(w)/M_(n) [g/mol] 70 58.3 205 2.0 249 50050 31.7 335 2.1 425 500

EXAMPLE 33

The procedure was as in Example 32, but the metallocene wasPh(Me)Si(2-methyl-4-phenyl-1-indenyl)₂ZrCl₂ and was employed as a 1:1meso:rac mixture. The results are collated in Table 5.

TABLE 5 Activity Polymerization [kg of PP/g of VI M_(w) temperature [°C.] metallocene x h] [cm³/g] M_(w)/M_(n) [g/mol] 70 112.5 559 3.5 738000 50 51.0 1084 3.6 1.35 · 10⁶

Fractionation of the polymer samples by ether extraction gave contentsof atactic polypropylene of 3.6% by weight (polymerization temperatureof 50° C.) and 7.0% by weight (polymerization temperature of 70° C.).The VI values were 158 and 106 cm³/g respectively.

The isolated atactic component had an elastomeric consistency and wascompletely transparent.

The polymer powder obtained from the polymerization is non-tacky, andmoldings produced therefrom have a good surface, are very transparentand do not exhibit fogging.

EXAMPLE 34

The process was as in Example 32, but the metallocene used wasrac/meso-Me₂Si(2-methyl-4-phenyl-1-indenyl)₂ZrCl₂ in supported form,with a rac:meso ratio of 1:1. The supported metallocene was prepared inthe following way:

a) Preparation of the Supported Cocatalyst

The supported cocatalyst was prepared as described in EP 92 107 331.8 inthe following way in an explosion-proofed stainless-steel reactor fittedwith a 60 bar pump system, inert-gas supply, temperature control byjacket cooling and a second cooling circuit via a heat exchanger in thepump system. The pump system drew the contents out of the reactor via aconnector in the reactor base into a mixer and back into the reactorthrough a riser pipe via a heat exchanger. The mixer was installed insuch a way that a narrowed tube cross-section, where an increased flowrate occurred, was formed in the feed line, and a thin feed line throughwhich—in cycles—in each case a defined amount of water under 40 bar ofargon could be fed in ran into its turbulence zone axially and againstthe flow direction. The reaction was monitored via a sampler in the pumpcircuit.

5 dm³ of decane were introduced under inert conditions into theabove-described reactor with a capacity of 16 dm³. 0.3 dm³ (=3.1 mol) oftrimethylaluminum were added at 25° C. 250 g of silica gel SD 3216-30(Grace AG) which had previously been dried at 120° C. in an argonfluidized bed were then metered into the reactor via a solids funnel andhomogeneously distributed with the aid of the stirrer and the pumpsystem. The total amount of 45.9 g of water was added to the reactor inportions of 0.1 cm³ every 15 seconds over the course of 2 hours. Thepressure, caused by the argon and the evolved gases, was kept constantat 10 bar by pressure-regulation valves. When all the water had beenintroduced, the pump system was switched off and the stirring wascontinued at 25° C. for a further 5 hours. The solvent was removed via apressure filter, and the cocatalyst solid was washed with decane andthen dried in vacuo. The isolated solid contains 19.5% by weight ofaluminum. 15 g of this solid (108 mmol of Al) were suspended in 100 cm³of toluene in a stirrable vessel and cooled to −30° C. At the same time,200 mg (0.317 mmol) of rac/meso 1:1Me₂Si(2-methyl-4-phenyl-indenyl)₂ZrCl₂ were dissolved in 75 cm³ oftoluene and added dropwise to the suspension over the course of 30minutes. The mixture was slowly warmed to room temperature withstirring, during which time the suspension took on a red color. Themixture was subsequently stirred at 70° C. for 1 hour, cooled to roomtemperature and filtered, and the solid was washed 3 times with 100 cm³of toluene in each case and once with 100 cm³ of hexane. Thehexane-moist filter residue which remained was dried in vacuo, giving14.1 g of free-flowing, pink supported catalyst. Analysis gave a contentof 11.9 mg of zirconocene per gram of catalyst.

b) Polymerization

0.7 g of the catalyst prepared under a) were suspended in 50 cm³ of abenzine fraction having the boiling range 100-120° C. from which thearomatic components had been removed.

In parallel, a dry 24 dm³ reactor was flushed first with nitrogen andsubsequently with propylene and filled with 12 dm³ of liquid propyleneand with 1.5 dm³ of hydrogen. 3 cm³ of triisobutylaluminum (12 mmol)were then diluted with 30 ml of hexane and introduced into the reactor,and the batch was stirred at 30° C. for 15 minutes. The catalystsuspension was subsequently introduced into the reactor, and thepolymerization system was heated to the polymerization temperature of70° C. (10° C./min) and kept at 70° C. for 1 hour by cooling. Thepolymerization was terminated by addition of 20 mol of isopropanol. Theexcess monomer was removed as a gas, and the polymer was dried in vacuo,giving 1.57 kg of polypropylene powder.

Fractionation of the polymer by ether extraction gave an ether-solubleatactic content of 8.9% by weight (VI=149 cm³/g) and an insolubleisotactic content of 91.1% by weight, with a VI of 489 cm³/g. The powderprepared in this way was non-tacky, and moldings produced therefrom donot exhibit fogging in the heat-aging test, and the hardness andtransparency of the moldings are very good.

Comparative Examples 1 to 10

Polymerization were carried out in a manner comparable to the aboveexamples using 1:1 rac:meso mixtures of metallocenes not according tothe invention at polymerization temperatures of 70° C. and 30° C. Theresultant polymers were likewise subjected to ether separation in orderto characterize the polymer components. The results are collated inTable 6 and show that in no case could a polymer according to theinvention having a high-molecular-weight atactic polymer component(ether-soluble component) be prepared. Products are generally tacky, andthe moldings produced therefrom are soft, have a speckled surface andexhibit considerable fogging.

TABLE 6 Polymer data Polymerization temperature 70° C. Polymerizationtemperature 30° C. Metallocene VI ether-soluble VI ether-insoluble VIether-soluble VI ether-insoluble rac: meso = 1:1 mixture [cm³/g] [cm³/g)[cm³/g] [cm³/g] Me₂Si(indenyl)₂ZrCl₂ 45 42 46 75Me₂Si(2-methyl-1-indenyl)₂ZrCl₂ 50 180 56 340 Methylethylene(2-methyl-1-56 127 59 409 indenyl)₂ZrCl₂ Ph(Me)Si(2-methyl-1- 50 202 57 501indenyl)₂ZrCl₂ Me₂Si(2-ethyl-1-indenyl)₂ZrCl₂ 59 187 61 443Me₂Si(2,4,5-trimethyl-1-cyclo- 45 50 47 236 pentadienyl)₂ZrCl₂Me₂Si(2,4,5-trimethyl-1-cyclo- 59 175 69 356 pentadienyl)₂HfCl₂Me₂Si(indenyl)₂HfCl₂ 61 237 63 398 Ethylene(2-methyl-1- 47 85 50 135indenyl)₂ZrCl₂ Me₂Si(2-methyl-4-t-butyl-1- 28 31 35 105cyclopentadienyl)₂ZrCl₂

Comparative Examples 11 to 21

Comparative Examples 1 to 10 were repeated using the pure meso-forms ofthe metallocenes used therein. Atactic polypropylene was obtained, butin no case was a viscosity index VI of >70 cm³/g obtained. Thesemetallocenes which are not according to the invention can thus not beused to prepare high-molecular-weight atactic polypropylene. Theproducts are liquid or at least soft and highly tacky.

What is claimed is:
 1. An olefin polymer which comprises an atacticpolymer having a viscosity index VI of >80 cm³/g, a molecular weightM_(w) of >100,000 g/mol, a poly-dispersity M_(w)/M_(n) of ≦4.0 and anisotactic index of ≦60%.
 2. An olefin polymer which comprises at leasttwo types of polyolefin chains: a) a maximum of 99% by weight of thepolymer chains comprise isotactically linked α-olefin units having anisotactic index of >90% and a polydispersity of ≦4.0, and b) at least 1%by weight of polymer chains comprise atactic polyolefins having anisotactic index of ≦60%, a viscosity index VI of >80 cm³/g, a molecularweight M_(w) of >100,000 g/mol and a polydispersity M_(w)/M_(n) of ≦4.0.3. The olefin polymer as claimed in claim 1, wherein a) the maximum of98% by weight of the polymer chains comprise isotactically linkedα-olefin units having an isotactic index of >90% and b) at least 2% byweight of polymer chains comprise atactic polyolefins.
 4. The olefinpolymer as claimed in claim 1, wherein the olefin polymer ispolyethylene.
 5. The olefin polymer as claimed in claim 1, wherein theolefin polymer is polypropylene.
 6. The olefin polymer as claimed inclaim 2, wherein the olefin polymer is polyethylene.
 7. The olefinpolymer as claimed in claim 2, wherein the olefin polymer ispolypropylene.
 8. An olefin polymer which comprises at least two typesof polyolefin chains: a) a maximum of 99% by weight of the polymerchains comprise isotactically linked olefin of the formulaR^(a)—CH═CH—R^(b) in which R¹ and R^(b) are identical or different andare a hydrogen atom or an alkyl radical having from 1 to 14 carbonatoms, and said olefin having an isotactic index of >90% and apolydispersity of ≦4.0 and b) at least 1% by weight of polymer chainscomprise atactic polyolefins having an isotactic index of ≦60%, aviscosity index VI of >80 cm³/g, a molecular weight M_(w) of >100,000g/mol and a polydispersity M_(w)/M_(n) of ≦4.0.
 9. The olefin polymer asclaimed in claim 8, wherein said olefin of the formula R¹—CH—CH—R^(b) isethylene, propylene, 1-butene, 1-hexene, 4-methyl-1-pentene, 1-octene,norbornene or norbonadiene.
 10. The olefin polymer as claimed in claim8, wherein the olefin polymer is polyethylene.
 11. The olefin polymer asclaimed in claim 8, wherein the olefin polymer is polypropylene.